Process for purifying lubricating oils by hydrogenation



May 7, 1968 F. 5. W000 ET AL 3,382,168

PROCESS FOR PURIFYING LUBRICATING OILS BY HYDROGENATION Filed March 1, 1965 I k g N) Q R Q rm m n N N I\ l N Q 5E A i; Q 3

/ INVENTORS:

Frederick S. Wood X Roland L. Menz/ s 8' Madison E. Marks t Qm g E Roger G. Garsf I a; g

United States Patent 3,382,168 PROCESS FOR PURIFYING LUBRICATING OILS BY HYDROGENATION Frederick S. Wood, Valparaiso, Roland L. Menzl, Harnmond, and Madison E. Marks, Chesterton, Ind, and Roger G. Garst, South Holland, 111., assignors to Standard Oil Company, Chicago, IlL, a corporation of Indiana Filed Mar. 1, 1965, Scr. No. 435,941 Claims. (Cl. 203-264) This invention relates to the finishing of lubricating oils. More particularly, it relates to the mild hydrogenation of lubricating oil stocks in the presence of a suitable hydrogenation catalyst and hydrogen to obtain products of high quality.

Through the years numerous refining methods for lubricating oils have been used. Many of these include lowpressure fractionation, solvent extraction, solvent dewaxing, acid treating, and clay treating. Such lubricating-oil treatments are discussed in Kirk-Othmer Encyclopedia of Chemical Technology, volume 10, The Interscience Encyclopedia, Inc., New York, pp. 147l53 (1953).

More recently, hydrotreating has been used as a means for improving the quality of raw lubricating-oil stocks. Such hydrogenation processes have been used generally to improve the color and the stability of the oil. They employ suitable hydrogenation catalysts. Typical catalysts for such hydrotreating are nickel-tungsten sulfide, cobalt molybdate, nickel molybdate, cobalt sulfide, molybdenum sulfide, and molybdenum oxide. These catalytic materials are generally supported on a suitable carrier or support such as alumina, magnesia, silica, or silica-alumina.

The present invention employs a suitable hydrogenation catalyst from the group which includes supported noble metals and metals of the Sixth and Eighth Groups of the Periodic Table and the oxides, sulfides, or mixture thereof. The preferred cata.yst for the process is a conventional cobalt-molybdenum hydrogenation catalyst which comprises the oxides of cobalt and molybdenum on an alumina support. A typical example of such a catalyst would contain from about 2 to 4 percent by weight cobalt oxide and from 10 to percent by weight of the oxides of molybdenum. Such catalysts and their preparation are well known in the art. Prior to its use in our invention, the catalyst may be activated by subjecting it to a sulfiding treatment.

Our invention may be used to treat both solvent-extracted lubricating-oil stocks and distillates. Such stocks may, or may not, have been previously dewaxed. Advantageously, our hydrotreating process can replace the acidtreating and clay-contacting steps in a presently-employed finishing scheme for lubricating-oil base stocks. For example, a finishing scheme which comprises phenol extraction, propane dewaxing and hydrogenation can successfully replace the presently-operable finishing scheme which comprises phenol extraction, propane dewaxing, acid treating, and clay contacting to produce similar grades of solvent-extracted base stocks. Furthermore, a finishing scheme for refining a distillate which comprises propane dewaxing and hydrogenation can replace the presently-operable finishing scheme which comprises propane dewaxing, acid treating and clay contacting of the same distillates.

Commercially-acceptable refined lubricating oils may be obtained by the hydrotreating of a variety of raw feeds. Among the feed stocks which can be treated by our invention are those that will provide hydrogenated solvent-extracted base stocks which have Say-bolt viscosities at F. of about 100, 165, 330, 840 and 1400 and which are used to make finished S.A.E. 5W, 10W, 20, 40 and 50 grade motor oils, respectively. In addition, our invention can be used successfully to treat those feeds which will provide hydrogenated dewaxed disti lates having Saybolt viscosities at 100 F. of about 50, 85, 220 and 530. For the production of each of the above lubricating-oil base stocks, the feed stock has been dewaxed.

Our invention is a process for the improvement of the quality of a lubricating oil which comprises the following steps: A hydrogen-containing gas is mixed with the hydrocarbon distillate stream which has been previously heated to a temperature within the range from about 325 F. to about 375 F. The temperature of this mixture of hydrocarbons and hydrogen-containing gas is then raised to a value within the range from about 500 F. to about 695 F. Hydrogen partial pressure is maintained Within the range from about 500 to about 1200 p.s.i.a. The heated mixture is then passed through a hydrogenation zone Where it is passed over and through a bed of a suitable hyd-rogenation catalyst at a liquid hourly space velocity within the range from about 0.25 to about 5.0 volumes of hydrocarbon per hour per volume of catalyst. The efiiuent from the hydrogenation zone is then cooled to a temperature that does not exceed F. The cooled efiluent is flashed in a two-stage step; first, at a high pressure and, second, at a low pressure. The liquid efiiuent from the flashing step is heated to a temperature within the range from about 500 F. to about 550 F. The cooling, flashing and heating steps are carried out such that the total time at which the efiluent from the hydrogenation zone is held at a temperature above 450 F. does not exceed a period of 4 minutes. A total time which is less than 4 minutes is preferred. The heated liquid efiluent from the flashing step is steam stripped at a temperature which is maintained below 650 F. to remove the hydrogen sulfide, ammonia, water, and other low boiling constituents.

Prior art processes have subjected the hydrotreated hydrocarbons to an elevated temperature for an extended period of time in order to furnish non-corrosive products. For example, see Mills, et al. US. Patent 2,846,356.

We have found surprisingly that the amount of time at which the hydrogenated hydrocarbon oil is subjected to an elevated temperature prior to stripping may be minimized and still provides non-corrosive products. A combination of rapidly cooling the eflluent from the hydrogenation zone and rapidly heating the effluent from the flashing step to a temperature that is being employed in the stripping section of the system provides a product that is non-corrosive, in addition to minimizing the thermal degradation of the hydrogenated product. It is highly advantageous to immediately strip the heated effiuent. However, there exists holdup in both the stripping and dehydrating sections of the system. Since the holdup time in both of these sections cannot be reduced further, minimization of the time during which the hydrogenated hydrocarbon oil exists at the elevated temperatures in the part of our system which extends from the hydrogenation zone to the stripping section is desired. Therefore, the residence time of the hydrogenated hydrocarbon oil is held to a minimum for each of the periods of cooling the hydrogenated oil prior to flashing and for heating the flashed efiluent prior to stripping.

-In a subsequent example we have shown that the hydrotreated hydrocarbons can be subjected, prior to stripping, to a temperature above 450 F. for a period of time as short as two minutes without the resultant product having corrosive properties. But it is more practical if the period at which the hydrotreated hydrocarbons are subjected to a temperature above 45 F. prior to stripping constitutes 3 to 4 minutes. Hence, we have established that the period at which the hydrotreated hydrocarbons prior to stripping are subjected to a temperature of 450 F. should not exceed 4 minutes. Periods less than 4 minutes are preferred.

The hydrogenation step of the present process is carried out at the following conditions: a temperature within the range from about 500 F. to about 695 F., preferably, from 550 F. to 650 F.; a liquid hourly space velocity within the range from about 0.25 to about 5.0 volumes of hydrocarbon per hour per volume of catalyst, preferably, from 0.5 to 1.0 volumes of hydrocarbon per hour per volume of catalyst; a hydrogen partial pressure within the range from about 500 to about 1200 p.s.i.a, preferably from 700 to 900 p.s.i.a.; a hydrogen consumption within the range from about standard cubic feet of hydrogen per barrel of hydrocarbon to about 300 standard cubic feet of hydrogen per barrel of hydrocarbon, preferably, from to 250 standard cubic feet of hydrogen per barrel of hydrocarbon; and a hydrogen flow to the reactor within the range from about to about 1000 standard cubic feet of hydrogen per barrel of hydrocarbon, preferably, from 200 to 800 standard cubic feet of hydrogen per barrel of hydrocarbon.

Various tests were performed to demonstrate those conditions which will provide satisfactory and efficient finishing of the lubricating oil stocks being treated. These tests were performed in an automated, continuous-flow hydrogenation unit and are discussed in the following examples. In this unit, a mixed stream of the hydrocarbon feed stock to be hydrogenated and once-through, substantially-dried hydrogen was introduced into the top of the reactor. The hydrogen, prior to its mixing with the hydrocarbons, was metered by a Jerguson-gauge-bubbleflow meter and dried by passage through a Deoxo-Drierite system. The mixed hydrogen and hydrocarbons were trickled down through a bed of cobalt-molybdenum hydrogenation catalyst within the reactor. The reactor effluent was cooled by a water-cooled condenser. The residence time of the hot hydrogenated product did not exceed three minutes. The cooled effiuent was conducted into a Jerguson separator, where the hydrogen was separated from the rest of the efiluent. Additional light material, hydrogen sulfide, water, and ammonia were removed from the efiluent in a stripper column and vented. The stripped product was then collected in one of three product receivers that were heated and nitrogen-blanketed. Nitrogen was used as the stripping medium, and the temperature and nitrogen rate of the stripper were regulated to provide flash-specification products. The stripper bottoms stream was discarded for an interval designated as the line-out period.

Catalyst was loaded into the reactor so that the bottom of the bed wa maintained at approximately the same position for all tests. The catalyst bed was supported by a two-inch layer of six-millimeter glass beads, which, in turn, was supported by a ten-mesh, stainless-steel screen and the bottom closure of the reactor. The reactor was 2.5 feet long and had an inside diameter of 1.5 inches. If the catalyst bed were composed of 500 cos. of catalyst, the bed would be approximately 17 inches long. The catalyst was charged to the reactor by slowly pouring it with gentle tapping into the top of the reactor. Immediately above the catalyst, 6-millimeter glass beads were placed; and this glass-bead section and was extended to within an inch of the top closure of the reactor. For each of the tests that were made in Examples I and II, A -inch cobalt-molybdenum catalyst was used. This catalyst was an extrudate and contained 3.4 weight percent cobalt oxide and 13.4 weight percent molybdenum oxide on an alumina carrier. Ordinarily, the catalyst was calcined at 900 to 1000 F. for a period of 2 to 4 hours prior to a sulfiding pretreatment. This sulfiding pretreatment was carried out in situ for 16 hours with an 8-mo1-percenthydrogen-sulfide, 92-mol-percent-hydrogen gas mixture. This gas mixture was introduced from gas cylinders and was added at a rate varying from 4 to 6 standard cubic feet per hour per liter of catalyst. The temperature during this sulfiding pretreatment was maintained within a range from 725 F. to 750 F. and the pressure wa held at a value slightly above that of atmospheric pressure.

Preliminary tests at low feed rates had indicated that poor contacting, with corresponding erratic results, had been obtained unless the catalyst was pre-wetted for at least 3 hours by pumping the hydrocarbon feed at a rate of at least 1500 ccs. per hour (this rate corresponds to a superficial linear velocity of approximately 4.3 feet per hour).

Example I An -viscosity Mid-Continent distillate was employed as the hydrocarbon feed stock in the tests that are included in Example I. This feed stock contained 0.55% sulfur and 165 p.p.m. basic nitrogen. In each of these tests, the hydrogen partial pressure was maintained at 815 p.s.i.a.; however, both the temperature and liquid hourly space velocity were varied. The Indiana Oxidation Test was used as a means of indicating the oxidation stability of the products.

The Indiana Oxidation Test is a method which is used to indicate the oxidation stability of lubricating-oil base stocks which contain no additives. The test determines the amount of naphtha-insoluble sludge which is formed during each of several successive periods. The primary purpose of such a test is to determine the sludging tendency of an oil, which is measured by the number of hours required to form 10 milligrams of sludge per 10 grams of treated solvent-refined oil, or by the milligrams of sludge formed in 24 hours per 10 grams of treated distillate. When a relatively stable oil is being tested, appreciable asphaltene formation requires from about 48 to about 200 hours to begin; however, once the formation has started, it may proceed quite rapidly. The 10-mg. sludge time was estimated by interpolation from a loglog plot of sludge content versus time over appropriate periods. When a less stable oil is being tested, the asphaltene formation begins earlier, and the sludge content at a particular time may be conveniently used for comparing oils. The particular length of time of 24 hours was selected for use in these tests. The test method was originally published by T. H. Rogers and B. H. Shoemaker in Ind. Eng. Chem. Anal. Ed., vol. 6, No. 6, p. 419 (June 1934). The method as described therein has been somewhat modified for this work. The principal modifications were a decrease in the size of the oil sample from 300 to cc. with a proportional decrease in the air fiow and an increase in the time of standing of the naphthasludge solution from 3 hours to 16-24 hours.

The results of the tests included in Example I are presented in Table I below.

TABLE I Test Catalyst loading, ee. (gr.) Line-out time, hours A B C These results demonstrate that the best color is obtained and less sludge is formed in the Indiana Oxidation Test by those oils in which a small amount of sulfur is retained. However, if too much ulfur is removed, sludge formation will be increased. This is also the case if insufficient sulfur is removed. In the example, the product in Test B, which contained 0.20% sulfur, formed only 40 mg. of sludge in 24 hours, while that in Test C, which contained only 0.07% sulfur, formed 100 mg. of sludge in 24 hours and the product in Test A, which contained 0.34% sulfur, formed 60 mg. of sludge in 24 hours. The more severe conditions of Test C and the less severe conditions of Test A resulted in less stable products than the product from Test B.

Example II In another series of tests, a 245-viscosity Mid-Continent distillate was used as the hydrocarbon feed stock. This distillate contained 0.62% sulfur and 240 p.p.m. of basic nitrogen. In these tests, the hydrogen pressure was maintained at 815 p.s.i.a. Both the temperature and liquid hourly space velocity were varied. The results of these tests are presented in Table II.

extruded cobalt-molybdenum catalyst was used in this test. The finished oil after hydrogenation possessed the following properties, which are compared with the railroad specifications for this particular lubricating oil.

TABLE III Property Specification Hydrotreated Oil Viscosity at- 210 F., SUS 82-86 84. 7 Flash point, COG, F 475 530 Pour point, F 2 I Color, ASTM D-1500 3. -4. 5 2. 8

1 Minimum. 2 Maximum.

Example IV TABLE H A number of tests were made to demonstrate the D D F ability of our process to produce refined lubricating oils Test and disttllates that Will meet corrosion s ecifications. The

n p Catalyst loading, cc. (gn) 4 0 (2g 50 (4 2 3 (2 following tests were performed in the automated unit g g'ggfi ggfi i f 17.5 12 described above. The hydrotreated product saw an ele- Temperlaturle, F 63; 67g 37g vated temperature, 1.e., a temperature above 450 F.. for lii ilt a i d t i t l i l sifl r lg. sludge no more than the estimated residence time disclosed. This C214hoRrsST I fi i5b6 g g period occurred following the hydrogenation zone and lg 1 0 F. 5, prior to the cooler and the stripper. The product from gulf ur tzchperceflt 1% 5 98 each test was sub ected to the copper-strip test ASTM D-130, wherein a copper strip was immersed i the hydrocarbons for 3 hours at a temperature of 212 F. The pertinent data are presented in Table IV.

TABLE IV Test G H I J K Feed Stock (dewaxed) Light dist. Med. dist. Heavy dist. Med. rat. Light dist.

Viscosity at 100 F., SUS so 245 670 365 50. 9 Catalyst volume, cc 400 650 400 400 400 Liquid hourly space velocity 3. 2 1. 0 l. 1 3. 2 0.5 Reactor pressure, p.s.1.g 800 800 500 800 00 Reactor temperature, F 595 675 675 640 563 Estimated residence time above 450 F., minutes 0.4 0.2 0.7 0.23 1.1 Copper-strip results la 1a 1a 1a 1a 1 Distillate. 2 Ratfinate.

Again, the product which contained the intermediate amount of sulfur proved to be the most stable as shown by the Indiana Oxidation Test. The test which used the most severe and the least severe conditions produced the less stable products.

Example III As an example of showing the effect of the substitution of our hydrogenation process for a step in a presentlyused oil-refining scheme, we shall consider the refining of an additive-free lubricating oil that has been produced for railroad use. This particular oil is made from a solventextracted stock having a Saybolt viscosity at 210 F. of 86 seconds. The present refining scheme of this lubricating oil included solvent refining, dewaxing and clay percolation. Our hydrogenation step was substituted for the clay-percolation step. The hydrogenation was carried out at the following conditions: the temperature was maintained at approximately 510 F.; the pressure, at 815 p.s.i.a.; and the liquid hourly space velocity, at 1.0 volume of oil per hour per volume of catalyst. The A -inch In each case, the results of the copper-strip test were In. These results show that the hydrotreated hydrocarbons can be subjected to the elevated temperature for a period not to exceed 2 minutes and still will be noncorrosive.

Example V To demonstrate the effectiveness of our hydrogenation process, several solvent-extracted oils, which are currently being finished by clay percolation, were hydrogenated rather than being percolated. These included a solvent-extracted grade-l0 oil, a solvent-extracted grade- 20 oil and a solvent-extracted gradeoil. In each case, the hydrogenation was carried out at a liquid hourly space velocity of 1, a reactor temperature of 600 F., and a hydrogen partial pressure of 815 p.s.i.a. Oxidation stability, col-or, and viscosity values were obtained. The results of these tests are presented in Table V. These results are compared to values that have been obtained with typical percolated oils and to the specification values for the particular percolated oil under consideration.

TABLE V.-HYDROGENATED REPLACEMENTS FOR PERCOLATED SOLVENT-EXT RACTED OILS 1 Indiana Oxidation Test, hours for grams of oil to produce 10 mg. of sludge. 2 ASTM D 043, all oils contained two oxidation inhibitors, 0.25% hindered phenol and 0.05% aromatic amine, and 0.1% rust inhibitor, on alkylated dicarboxylic acid.

3 Minimum. 4 Maximum.

These data show that the hydrogenated material does meet the present specification for a particular oil and does provide a finished product which is at least equivalent to the percolated oil.

More severe hydrogenation conditions will produce products which have even greater stability, but will incur a slightly greater viscosity loss. For example, a solventextracted 40 raffinate that has been hydrogenated at a liquid hourly space of /2 volumes of oil per hour per volume of catalyst, a reactor temperature of 635 F., and a hydrogen partial pressure of 815 p.s.i.a. gives an Indiana-Oxidation-Test value of 145 hours; with the same additives as the oils in Table V, a TurbineOil-Test value of 3000 hours; a viscosity of 75 S.U. Seconds at 210 F.;

and a viscosity index of 93.

The above examples suggest that our lubricating-oil hydrogenation process can replace satisfactorily the acidtreating and/or clay-percolation steps that are employed in current refinery operations for finishing lubricating oils. In addition, the results show that a non-corrosive product can be obtained through the use of our hydrogenation process.

One may more easily understand our inventi n through the use of the accompanying figure. This figure is a schematic flow diagram of a specific embodiment of our process.

A dewaxed distillate having a viscosity of 670 S.U.S. at 100 F. is hydrogenated in this specific embodiment. Referring to the figure, 2250 barrels of feed per stream day (BSD) are pumped from line 11 by pump 12 through line 13 into filter 14. The filtered feed is passed through line 15 into heat exchanger 16, where its temperature is raised from 150 F. to about 350 F. The heated oil is then passed through line 17, where it is commingled with a hydrogen-containing reformer off-gas. The reformer offgas is fed through line 18 into compressor 19, where it is compressed to a pressure which exceeds 200 p.s.i.g. The pressurized gas is introduceddnto line 17 via line 20. The commingled hydrogen-containing gas and the hydrocarbon feed stock pass through line 17 into furnace 21. The mixture is heated to a temperature which does not exceed 640 F.

The heated mixture then is passed through line 22 into the top of reactor 23. The hydrogen partial pressure in both furnace 21 and reactor 23 is maintained at approximately 815 p.s.i.a. Three distinct beds of catalyst are contained in reactor 23. The preferred cobalt-molybdenum hydrogenation catalyst is em loyed. The heated mixture passes down through the three catalyst beds. The combined weight of catalyst in the three beds is 48,000 pounds. Each of the beds is followed by a layer of alumina. Even though the heat of reaction is relatively small, feed as coolant may be introduced into the reactor by way of line 24 in order to provide a more uniform reaction temperature, it such operation is desirable. The

hydrogenated efiiuent is exited from the bottom of reactor 23 through line 25 into heat exchanger 26 where its temperature is reduced to a value which does not exceed 445 F. The design of the equipment permits the hot hydrocarbons to be cooled to a temperature below 450 F. within an estimated time of 1.3 minutes. The material is passed through line 27 into heat exchanger 16, where its temperature is further reduced to a value that does not exceed 275 F. The material is then passed through line 28 into condenser 29, where it is further cooled to a temperature which does not exceed 150 F.

The cooled product is passed through line 30 into a high-pressure flash drum 31, wherein the pressure is maintained at approximately 950 p.s.i.g. The high-pressure flash gas is vented from the system by way of line 32, or may be recycled to be used as a source of hydrogen, if desired. This high-pressure flash gas contains substantial amounts of hydrogen sulfide, sometimes as much as 10.5 weight percent. The product exiting from the bottom of the flash drum 31 is passed through line 33 into low pressure flash drum 34. The low-pressure flash gas is withdrawn from the top of flash drum 34 through line 35 to be used as fuel, while the rest of the product is passed from the bottom of flash drum 34 via line 36 into heat exchanger 37.

The temperature of the material is heated in heat ex changer 37 to a temperature that does not exceed 365 F. The heated material is then passed through line 38 into heat exchanger 26, where it is heated to a temperature that does not exceed 525 F. The equipment is so designed that the raising of the temperature of the hydrotreated lubricating oil from approximately 148 F. to 525 F. takes place within a time in which the residence time of the hydrocarbons at temperatures above 450 F. is estimated not to exceed 2.5 minutes.

Therefore, in this specific embodiment, the total time at which the hydrogenated lubricating oil stock is at a temperature above 450 F. prior to stripping is estimated to be 3.8 minutes. This period at elevated temperatures may be broken down into a cooling period of 1.3 minutes and a heating period of 2.5 minutes.

This product, now at a temperature of approximately 525 F., is passed through line 39 into stripper 40. Steam is introduced into stripper 40 by way of line 41 at a rate of about 800 pounds per hour. The stripped hydrocarbon stream is withdrawn from the bottom of stripper 40 through line 42 and should possess a temperature which does not exceed 510 F. Condensate is removed from the conventional recycle system of stripper 40 by way of line 43. The stripped hydrogenated distillate is pumped by pump 44 through line 45 into vacuum dehydrator 46 where excess water is removed from the hydrocarbon product. Water, as steam, is removed from the system through line 47. The dehydrated distillate is then passed from dehydrator 46 through line 48 into pump 49. The

hydrocarbons are pumped by pump 49 through line 50 into heat exchanger 37, where their temperature is cooled to a maximum value of 300 F. The cooled product is then passed through lines 51 and 53 and filter 52 into condenser 54, where additional cooling occurs to a maximum temperature of 150 F. Approximately 2250 BSD of prod net are obtained from the system via line 55.

From time to time, the cobalt-molybdenum catalyst will require regeneration to remove the accumulated coke. Such regeneration can be advantageously carried out by the use of a mixture of steam and air. For example, steam at approximately 750 F. can be introduced into the top of reactor 23 by way of lines 56, 17 and 22 and furnace 21. Air may be added to this steam vial line 57 to provide a preferred oxygen concentration of approximately 1 /2 (by volume). The regeneration is controlled so that a flame front will pass down through the catalyst bed or beds. This regeneration procedure is continued until a flame front has passed through all of the catalyst. Preferably, the temperature at any particular point in the catalyst bed or beds is not to exceed 1000 F. in order to prevent localized overheating of the catalyst.

We have presented the above specific embodiment of our invention primarily for descriptive purposes. We do not intend that it limit or restrict our invention. Various modifications and alterations of the processing scheme, which shall not interfere with our invention, may be readily applied by those skilled in the art. For example, the heat transfer system may be altered.

Reasonable variation and modification are possible within the scope of the above disclosure, drawing, and appended claims.

We claim:

1. Process for the improvement of the quality of a petroleum lubricating oil, which process comprises: hydrotreating said lubricating oil, said hydrotreating consisting of heating a mixture of said lubricating oil and a hydrogencontaining gas, and treating said mixture in a hydrogenation zone under hydrogenation conditions and in the presence of a hydrogenation catalyst, said hydrogenation conditions including a temperature within the range from about 500 F. to about 695 F., a hydrogen partial pressure within the range from about 500 to about 1200 p.s.i.a., a liquid hourly space velocity within the range from about 0.25 to about 5.0 volumes of hydrocarbon per hour per volume of catalyst, a hydrogen consumption within the range from about to about 300 standard cubic feet of hydrogen per barrel of hydrocarbon, and a hydrogen flow into said hydrogenation zone within the range from about 50 to about 1000 standard cubic feet of hydrogen per barrel of hydrocarbon, and said catalyst comprising hydrogenation components selected from the group which consists of metals of the Sixth and Eighth Groups of the Periodic Table and the oxides, sulfides, and mixtures thereof on a suitable catalyst support; separating gaseous materials from the effluent from said hydrogenation zone with the proviso that the period of time during which liquid efliuent is maintained-at a temperature above 450 F. during said separating and prior to stripping is not more than 4 minutes; and thereafter stripping the resulting liquid etfluent.

2. The process of claim 1 wherein said catalyst is a cobalt-molybdenum catalyst which comprises from about 2 to about 4 percent by weight of cobalt oxide and from about 10 to percent by weight of molybdenum oxide on an alumina base.

3. The process of claim 1 wherein said lubricating oil is dewaxed prior to its use in said process.

4. Process for the improvement of the quality of a petroleum lubricating oil, which process comprises: hydrotreating said lubricating oil, said hydrotreating consisting of heating a mixture of said lubricating oil and a hydrogencontaining gas, and treating said mixture in a hydrogenation zone under hydrogenation conditions and in the presence of a hydrogenation catalyst, said conditions including a temperature within the range from about 500 F. to about 695 F., a hydrogen partial pressure within the range from about 500 to about 1200 p.s.i.a., a liquid hourly space velocity within the range from about 0.25 to about 5.0 volumes of hydrocarbon per hour per volume of catalyst, a hydrogen consumption within the range from about 10 to 300 standard cubic feet of hydrogen per barrel of hydrocarbon, and a hydrogen flow into said hydrogenation zone within the range from about 50 to about 1000 standard cubic feet of hydrogen per barrel of hydrocarbon, and said catalyst comprising components selected from the group which consists of metals of the Sixth and Eighth Groups of the Periodic Table and the oxides, sulfides, and mixtures thereof on a suitable catalyst support; separating gaseous materials from the efiiuent from said hydrogenation zone with the proviso that the period of time during which liquid eflluent is maintained at a temperature above 450 F. during said separating and prior to stripping is not more than 4 minutes, said separating consisting of rapidly cooling the effluent from said hydrogenation zone to a temperature not to exceed F., flashing in a first flashing zone the cooled eflluent from said hydrogenation zone at a pressure within the range from about 900 to 975 p.s.i.g. to remove substantial amounts of hydrogen, hydrogen sulfide and other light constituents therefrom, flashing in a second flashing zone the liquid efiiuent from said first flashing zone at a pressure not to exceed 50 p.s.i.g., and rapidly heating the liquid effluent from said second flashing zone to a stripping temperature within the range from about 500 F. to about 550 F.; and immediately steam stripping the heated liquid efliuent from said second flashing zone to remove hydrogen sulfide, ammonia and other low-boiling constituents, the temperature of said steam stripping being maintained below about 650 F.

5. The process of claim 4 wherein said catalyst is a cobalt-molybdenum catalyst which comprises from about 2 to about 4 percent by weight of cobalt oxide and from about 10 to 15 percent by weight of molybdenum oxide on an alumina base.

6. The process of claim 4 wherein said lubricating oil is dewaxed prior to its use in said process.

7. Process for the improvement of the quality of a petroleum lubricating oil, which process comprises: hydrotreating said lubricating oil, said hydrotreating consisting of heating said lubricating oil to a temperature within the range from about 325 F. to about 375 F.; introducing into said lubricating oil a hydrogen-containing gas, said gas being added to furnish hydrogen within the range from about 50 to 1000 standard cubic feet of hydrogen per barrel of hydrocarbon, heating the resulting mixture of said lubricating oil and said gas to a temperature within the range from about 500 F. to about 695 F. at a hydrogen partial pressure within the range from about 500 to about 1200 p.s.i.a.; passing the heated mixture of said lubricating oil and said gas through a hydrogenation zone, said hydrogenation zone containing therein a hydrogenation catalyst and being maintained at a temperature within the range from about 500 F. to about 695 F. and a hydrogen partial pressure within the range from about 500 to about 1200 p.s.i.a., said lubricating oil being passed through said hydrogenation zone at a liquid hourly space velocity within the range from about 0.25 to about 5.01 volumes of hydrocarbon per hour per volume of catalyst and said hydrogen being consumed at the rate of about 10 to about 300 standard cubic feet of hydrogen per barrel of hydrocarbon, said catalyst comprising hydrogenation components selected from the group which consists of metals of the Sixth and Eighth Groups of the Periodic Table and the oxides, sulfides, and mixtures thereof on a suitable catalyst support; separating gaseous materials from the eflluent from said hydrogenation zone with the proviso that the period of time during which liquid efiiuent is maintained at a temperature above 450 F. during said separating and prior to stripping is not more than 4 minutes, said separating consisting of rapidly cooling the etfluent from said hydrogenation zone to a temperature not to exceed 150 F., flashing in a first flashing zone the cooled eflluent from said hydrogenation zone at a pressure within the range from about 900 to 975 p.s.i.g. to remove substantial amounts of hydrogen, hydrogen sulfide and other light constituents therefrom, flashing in a second flashing zone the liquid efliuent from said first flashing zone at a pressure not to exceed 50 p.s.i.g., and rapidly heating the liquid efiluent from said second flashing ZOne to a stripping temperature within the range from about 500 F. to about 550 F.; and immediately steam stripping the heated liquid eflluent from said second flashing zone to remove hydrogen sulfide, ammonia and other low-boiling constituents, the temperature of said steam stripping being maintained below about 650 F.

8. The process of claim 7 wherein said catalyst is a cobalt-molybdenum catalyst which comprises from about 2 to about 4 percent by weight of cobalt oxide and from about 10 to 15 percent by weight of molybdenum oxide on an alumina base.

9. The process of claim 8 wherein the operating conditions in said hydrogenation zone are a temperature with in the range from about 550 F. to about 650 E, ahydrogen partial pressure within the range from about 700 to about 900 p.s.i.a., a liquid hourly space velocity within the range from about 0.5 to about 1.0 volume of hydrocarbon per hour per volume of catalyst, a hydrogen consumption within the range from about 20 to about 250 standard cubic feet of hydrogen per barrel of hydrocarbon, and a hydrogen flow into the reactor within the range from about 200 to about 800 standard cubic feet of hydrogen per barrel of hydrocarbons.

10. The process of claim 7 wherein said lubricating oil is dewaxed prior to its use in said process.

References Cited UNITED STATES PATENTS 2,904,505 9/1959 Cole 208264 2,917,448 12/1959 Buether et al. 208264 3,016,350 1/1962 Butler et a1 208264 SAMUEL P. JONES, Primary Examiner.

DELBERT E. GANTZ, Examiner.

I M. Fletcher, Jr.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3 ,382 ,168 May 7 1968 Frederick S. Wood et 221.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, line 74, glass-bead section and was extended" should read glass-bead section was extended Column 6, line 43, "Med. dist. should read Med. dist.

Signed and sealed this 13th day of January 1970.

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Commissioner of Patents Attesting Officer WILLIAM E. SCHUYLER, R. 

1. PROCESS FOR THE IMPROVEMENT OF THE QUALITY OF A PETROLEUM LUBRICATING OIL, WHICH PROCESS COMPRISES: HYDROTREATING SAID LUBRICATING OIL, SAID HYDROTREATING CONSISTING OF HEATING A MIXTURE OF SAID LUBRICATING OIL AND A HYDROGENCONTAINING GAS, AND TREATING SAID MIXTURE IN A HYDROGENATION ZONE UNDER HYDROGENATION CONDITIONS AND IN THE PRESENCE OF A HYDROGENATION CATALYST, SAID HYDROGENATION CONDITIONS INCLUDING A TEMPERATURE WITHIN THE RANGE FROM ABOUT 500*F. TO ABOUT 695*F., A HYDROGEN PARTIAL PRESSURE WITHIN THE RANGE FROM ABOUT 500 TO ABOUT 1200 P.S.I.A., A LIQUID HOURLY SPACE VELOCITY WITHIN THE RANGE FROM ABOUT 0.25 TO ABOUT 5.0 VOLUMES OF HYDROCARBON PER HOUR PER VOLUME OF CATALYST, A HYDROGEN CONSUMPTION WITHIN THE RANGE FROM ABOUT 10 TO ABOUT 300 STANDARD CUBIC FEET OF HYDROGEN PER BARREL OF HYDROCARBON, AND A HYDROGEN FLOW INTO SAID HYDROGENATION ZONE WITHIN THE RANGE FROM ABOUT 50 TO ABOUT 1000 STANDARD CUBIC FEET OF HYDROGEN PER BARREL OF HYDROCARBON, AND SAID CATALYST COMPRISING HYDROGENATION COMPONENTS SELECTED FROM THE GROUP WHICH CONSISTS OF METALS OF THE SIXTH AND EIGHTH GROUPS OF THE PERIODIC TABLE AND THE OXIDES, SULFIDES, AND MIXTURES THEREOF ON A SUITABLE CATALYST SUPPORT; SEPARATING GASEOUS MATERIALS FROM THE EFFLUENT FROM SAID HYDROGENATION ZONE WITH THE PROVISO THAT THE PERIOD OF TIME DURING WHICH LIQUID EFFLUENT IS MAINTAINED AT A TEMPERATURE ABOVE 450*F. DURING SAID SEPARATING AND PRIOR TO STRIPPING IS NOT MORE THAN 4 MINUTES; AND THEREAFTER STRIPPING THE RESULTING LIQUID EFFLUENT. 